Noncorrosive metal cleaning composition



Patented June 10, 1952 NONCORROSIVE METAL CLEANING COMPOSITION John H. Seerist Detroit, Mich., assignor to Detrex Corporation, Detroit, Mich., a corporation 7 of Michigan No Drawing. Application August 26, 1947,

Serial No. 770,751 I 1 Claim. 1

This invention relates to the prevention of corrosion in the use of cleaning compositions containing a chlorinated hydrocarbon and water where such compositions are used in cleaning certain metals which are particularly susceptible to corrosion.

In a copending application which, bears Serial No. 752,568, filed June 4, 1947, now Patent No. 2,576,419 issued November 27, 1951, there is described a solvent composition which is useful in the cleaning of fabrics and various metals. The cleaning composition referred to contains a chlorinated hydrocarbon such as trichlorethylene as a solvent, water in a predetermined amount and a coupler such as monoethanolamine oleate for combining the solvent and the water in a subemulsion form characterized by the fact that the final composition is a perfectly clear, non-turbid, easily flowing liquid. One of the advantageous characteristics of such a sub-emulsion cleaner is that most metals, even where cleaned by the method known in the art as vapor degreasing, are not adversely effected by corrosive effects at the surface of the metal being cleaned eVen though water is present in the composition. However, it has been found that some metals, notably zinc and steel, show corrosive effects when cleaned with such sub-emulsion compositions under certain conditions which are sometimes encountered in the metal cleaning field.

The principal object of the present invention is to provide a suitable corrosion inhibitor to be used as one of the components of such cleaning compositions for the prevention of corrosion in the cleaning of metals such as zinc and steel.

It has been found that the objects of the present invention are achieved by the use of benzyl thiocyanate, sometimes referred to as benzyl sulfocyanide. This compound is highly effective in relatively small amounts in the prevention of corrosion of metals cleaned with sub-emulsion solvents of the type hereinafter described.

In carrying out the present invention, benzyl thiocyanate is added to the previously prepared sub-emulsion composition in an amount sufficient to inhibit corrosive action on metals such as zinc and steel. The amount of inhibitor may vary from 0.1 gram to 5.0 grams per 100 cc. of solvent depending on the length of time over which corrosion must be inhibited. The following examples is given as representative of the subemulsion and of the amount of inhibitor used, but it will be understood that considerable variation in the amounts of inhibitor is permissible and that the composition of the sub-emulsion may be Example Trichlorethylene (stabilized) cc Triethanolamine oleate grams 2 Monoethanolamine oleate do 6 Sodium oleate do 1 Water cc 11 The above ingredients are mixed by first dissolving the triethanolamine oleate and the monoethanolamine oleate in the trichlorethylene. The sodium oleate is then separately dissolved in the water and this solution is mixed with vigorous agitation with the previously prepared trichlorethylene solution until a non-turbid sub-emulsion is formed. The formation of the sub-emulsion may be accelerated by applying heat. The final liquid composition is perfectly clear, and has a specific gravity of 1.38. It will be noted that the chlorinated hydrocarbon used in the above example, namely trichlorethylene, is designated as Stabilized. Such stabilization is in addition to the inhibition of corrosion and is particularly desirable where the finished composition is to be used in vapor degreasing operations. Stabilization may be accomplished by the addition of small amounts of known stabilizers such as pyridine or triethylamine as described and claimed in U. S. Patent Number 2,096,735. Where other chlorinated hydrocarbons such as tetrachlorethylene (perchlorethylene) are used in producing the subemulsions referred to, it may be desirable to use other stabilizers as described in U. S. Patent 2,096,735.

To the above composition there is added 3.0 grams of benzyl thiocyanate as a corrosion in hibitor. The inhibitor is thoroughly mixed with the sub-emulsion by stirring and the finished composition i then ready for use in the cleaning of metals. This is carried out in metal cleaning apparatus well known to the art and comprises passing the metal to be cleaned through the stabilized liquid solvent or through hot, vaporized solvent or both.

The term sub-emulsion" as used throughout this specification and the appended claim is intended to define a composition containing a chlorinated hydrocarbon to which water has been coupled in an amount and in a way which re sults in a perfectly clear, non-turbid, easily flowing liquid. In some cases such sub-emulsions may be colored but even where colored there is an absence of visible particles or turbidity. Number I claim: 1,916,289 A noncorrosive metal cleamng composition 2,096,735 consisting of the following ingredients in sub- 5 2096736 stantially the proportions specified: 2,203,649 Trichlorethylene (stabilized) cc 100 2353665 Triethanolamine oleate grams 2 2,333,114 Monoethanolamine oleate do 6 10 Sodium oleate do 1 Number Water -cc 11 608 928 Benzyl thiocyanate "grams" 3 JOHN H. SECRIST.

REFERENCES CITED 4 UNITED STATES PATENTS Name Date Reddish May 30, 1933 Dinley Oct. 26, 1937 Dinley Oct. 26, 1937 Felkers June 4, 1940 Shapiro Sept. 19, 1940 De Villiers Aug. 21, 1945 FOREIGN PATENTS Country Date Germany Feb. 4, 1935 OTHER REFERENCES 5 Emulsions: Booklet of Carbide & Carbon Chem.

Corp., N. Y., 1930, pgs. 19 and 21-3.

The following references are of record in the file of this patent: 

